Any examples for String or Arrays?

[raghu-d32]

Hi,
How do we export Strings or Arrays from the java file using JWebAssembly? Any ideas? Please let me know.

How to get something like the below code working?

@Export
public static String appendStrs(String a, String b){
    return a+b;
}

or maybe something with arrays like:

@Export
public static int[] sendArray(){
    int[] arr = {1,2,3,4};
    return arr;
}

Thanks

[Horcrux7]

The Java String and the JavaString are different object types. Can be that will be changed with https://github.com/WebAssembly/stringref

Until there is another solution you can use:
JSObject.domString(str) and JSObject.toJavaString(str)
https://github.com/i-net-software/JWebAssembly-API/blob/master/src/de/inetsoftware/jwebassembly/web/JSObject.java

Can be that this signatures will be change because it is a hack from the first days.

I think the int[] as return value should work without any hacks. On the JavaScript side you should receive an Int32Array.

[raghu-d32]

Hi
Using int[] as return type gives the following error:
Uncaught (in promise) TypeError: import object field 'NonGC' is not an Object

And using String anywhere gives this error:

de.inetsoftware.jwebassembly.WasmException: Abstract or native method can not be used: java/security/AccessController.doPrivileged(Ljava/security/PrivilegedAction;)Ljava/lang/Object;
If you want to use classes with native code, you must use a library that implements these native methods, such as 'de.inetsoftware:jwebassembly-api:+'.
	at java.security.AccessController.doPrivileged(AccessController.java)

Can you please help with the array or string implementations? or maybe a working example would be good.

Thanks

[Horcrux7]

Uncaught (in promise) TypeError: import object field 'NonGC' is not an Object

Sounds like that you does not have use the generated JavaScript: https://github.com/i-net-software/JWebAssembly/wiki/Getting-Started#html-template

de.inetsoftware.jwebassembly.WasmException: Abstract or native method can not be used: java/security/AccessController.doPrivileged(Ljava/security/PrivilegedAction;)Ljava/lang/Object;
If you want to use classes with native code, you must use a library that implements these native methods, such as 'de.inetsoftware:jwebassembly-api:+'.
at java.security.AccessController.doPrivileged(AccessController.java)

Sounds like that you does not have use the needed library jwebassembly-api: https://github.com/i-net-software/JWebAssembly/wiki/Getting-Started#add-dependency-to-api

What should the error message be to make it clear that the library is missing?

[raghu-d32]

I am not able to generate something like HelloWorld.wasm.js file.

This is my main code:

File wasmFile = new File("test.wasm");
JWebAssembly jWebAssembly = new JWebAssembly();

Class addClass = Add.class;
URL url = addClass.getResource(
        '/' +
                addClass.getName().replace('.', '/') +
                ".class");

jWebAssembly.addFile(url);
jWebAssembly.compileToBinary(wasmFile);

Is this the right way? How to generate js and html files?

[Horcrux7]

Do you want write your own build system? This is high level for the beginning. Why do you does not use Gradle for building?

You must also set library (addLibrary). If you does not have write your own then you need to use jwebassembly-api.jar

Is this the right way? How to generate js and html files?

Which files are produced? The HTML file with your base structure must you write self.

[raghu-d32]

I have used gradle build
This is my build.gradle:

plugins {
    id 'java'
    id "de.inetsoftware.jwebassembly" version "+"
}

apply plugin: 'de.inetsoftware.jwebassembly'

group 'org.example'
version '1.0-SNAPSHOT'

archivesBaseName = 'MyTestProj'

repositories {
    mavenCentral()
    maven { url 'https://jitpack.io' }
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'

    implementation 'de.inetsoftware:jwebassembly-compiler:+'
    implementation 'de.inetsoftware:jwebassembly-api:+'

}

test {
    useJUnitPlatform()
}

sourceSets {
    main {
        java {
            srcDir 'src/main/java'
        }
    }
}

wasm {
    //Get more debug information if there are problems.
    //logging.level = LogLevel.DEBUG

    //Change the output format to the text format *.wat.
    //This can be helpful to understand the problems if you see the generated code as text format.
    //format = 'text'

    //The used JWebAssembly compiler version. The default is the latest release '+'.
    //You can set any valid Gradle version string or a full dependency string.
    //The snapshot version is recommended until a stable release.
    compilerVersion = 0.4
    //compilerVersion = 'com.github.i-net-software:jwebassembly:master-SNAPSHOT'

    //Write method and parameter names into the output *.wasm file.
    //The file will be approximate 10% larger. And it generate a source map.
    //With a source map you can see in the debugger of the browser your source code if available.
    debugNames = true

    //Set an absolute or relative path between the final wasm file location and the source files location.
    ///This is needed for debugging in the browser. It work only if debugNames = true.
    //sourceMapBase = '../../src/main/java/'
    sourceMapBase = '/src/main/java/'
}

Is this the right way? Still after doing this no files are generated.

[Horcrux7]

If you want use the release version 0.4 of the API and not the snapshot version this can work. You will know it if you run it.

[Horcrux7]

Do you have solve your problem? If not what is the console output of your Gradle script?

[raghu-d32]

Yes we finally were able to run the gradle task 'wasm' and generate the required files. Used version master-SNAPSHOT instead of 0.4. Then it worked. Thanks for the help. Will get back to you if there an any issues.